Particle Beam Radiation Therapy Promising but Unproven for Treating Cancer

Particle beam radiation therapy, a technology used to treat several types of cancer, is considered by some clinicians to be better than traditional radiation, but there is limited evidence about its safety compared with other types of radiation therapy, according to a new comparative effectiveness report funded by the Department of Health & Human Services' (HHS) Agency for Healthcare Research and Quality (AHRQ)."

As technologies develop and new clinical interventions arise, it is important to balance access to potentially beneficial new technologies with ongoing research and evaluation to determine whether the technologies deliver what they promise," said AHRQ Director Carolyn M. Clancy, M.D. "Increased funding for comparative effectiveness research is an exciting opportunity to continue important research on medical therapies and interventions."

Particle beam radiation therapy, also known as charged particle radiation therapy or proton beam radiation therapy, uses beams of protons or other charged particles for cancer radiation treatment. This therapy is an alternative to other types of cancer radiation therapy such as external radiotherapy with ionizing photon (X- or gamma-ray) beams or brachytherapy with implanted radioactive sources.

All types of radiation therapy can harm both cancerous and healthy tissues, so clinicians strive to target the radiation to the cancer while avoiding adjacent healthy tissues. This is particularly important for tumors adjacent to critical body parts such as those in the eye, brain, head and neck. Particle beam radiation therapy can target the radiation with a high degree of precision, but its potential advantages over other radiotherapy alternatives have not been verified in long-term outcome studies, according to the new AHRQ technical brief.

Particle beam radiation therapy was introduced as an experimental treatment in the 1950s but was not cleared for widespread use by the U.S. Food and Drug Administration until 2001. The technology is very expensive—an estimated $175 million for each device—and is usually only available in large academic medical centers. Only seven centers in the United States currently provide the therapy, with an additional center currently under construction and expected to be operational by 2010. Although details have not been disclosed, several other hospitals are considering developing smaller treatment facilities based on upcoming technologies that have not yet been cleared by the Food and Drug Administration.

The technical brief did not indicate that particle beam radiation therapy is riskier than conventional radiation therapy. However, most studies about the therapy were conducted on small numbers of patients and did not compare the safety of particle beam radiation therapy against other therapies. For many cancers other than head and neck cancers, there are not enough comparative studies in the literature to base an evaluation of the clinical or cost effectiveness of particle beam radiation therapy compared with other treatments.

AHRQ is currently reviewing scientific studies on radiation therapies for head and neck cancers that will evaluate the clinical effectiveness of particle beam radiation therapy for those cancers.

The report is the Agency's first in a series of technical briefs—rapid-turnaround reports that summarize key issues regarding emerging treatments. Technical briefs highlight where more research is needed and where research may be sufficient to warrant a full systematic review. Technical briefs are produced by AHRQ's Effective Health Care program. Future technical briefs will describe the evidence on fetal surgery, stereotactic surgery for non-brain cancers and percutaneous heart valves.

AHRQ's new report, Technical Brief: Particle Beam Radiation Therapies for Cancer, is the newest research review from the Agency's Effective Health Care program. That program, authorized by the Medicare Prescription Drug, Improvement and Modernization Act, represents an important federal effort to compare alternative treatments for health conditions and make the findings public. The program is intended to help patients, doctors, nurses, pharmacists and others choose the most effective treatments.